Over the past five years, a computer raster display has been used to represent the surface structure of macromolecules. Shaded spheres are the primitives of the representation. In globular protein and nucleic acid structures, each sphere represents one atom or at times one amino acid. In representing viruses, the sphere primitive has been used in some cases to represent one whole protein. In other cases, the spheres are used to represent the shape of a portion of a protein. Symmetry of the viruses plays an important part in making the computer model look realistic. Once the shape of a protomer is modeled, it is then iterated over the (icosahedral) symmetry of the assembly. A model of limulus hemocyanin has been constructed starting from image-enhanced electron microscope data. Twenty shperes are used to represent the kidney bean shape of each of the 48 70,000-dalton proteins in the assembly. Fifty spheres were used to represent the low resolution shape of the muscle actin obtained from electron diffraction. The generalization of surface shape representation obtained using spheres as primitives indicates that it will be possible to model sub-cellular organizations by computer.